Method and apparatus for determining control actions based on tool health and metrology data

Abstract

A method for controlling a process includes processing a first workpiece in a first process tool. An output characteristic of the first workpiece is measured. A second workpiece is processed in the first process tool. A tool health metric is determined for the first process tool corresponding to the processing of the second workpiece. A control action is determined based on the measured output characteristic and the tool health metric.

What is claimed:  
     
       1. A method for controlling a process, comprising: 
       processing a first workpiece in a first process tool;  
       measuring an output characteristic of the first workpiece;  
       processing a second workpiece in the first process tool;  
       determining a tool health metric for the first process tool corresponding to the processing of the second workpiece;  
       determining a control action based on the measured output characteristic and the tool health metric.  
     
     
       2. The method of  claim 1 , wherein generating the control action further comprises generating a feedback control action for the first process tool. 
     
     
       3. The method of  claim 2 , wherein generating the feedback control action further comprises determining an operating recipe parameter of the first process tool for processing a subsequent workpiece. 
     
     
       4. The method of  claim 1 , wherein generating the control action further comprises generating a feedforward control action for a second process tool to process at least the second workpiece. 
     
     
       5. The method of  claim 4 , wherein generating the feedforward control action further comprises determining an operating recipe parameter of the second process tool for processing the second workpiece. 
     
     
       6. The method of  claim 1 , wherein generating the control action further comprises generating the control action in accordance with a control equation based on at least the measured output characteristic. 
     
     
       7. The method of  claim 6 , wherein generating the control action further comprises reducing a sensitivity of the control equation based on the tool health metric. 
     
     
       8. The method of  claim 7 , wherein reducing the sensitivity further comprises reducing a gain constant of the control equation. 
     
     
       9. The method of  claim 7 , wherein reducing the sensitivity further comprises reducing the sensitivity responsive to the tool health metric being less than a predetermined threshold. 
     
     
       10. The method of  claim 7 , wherein reducing the sensitivity further comprises reducing the sensitivity in proportion to a difference between the tool health metric and a predetermined threshold. 
     
     
       11. The method of  claim 6 , wherein generating the control action further comprises generating an offset value for the control equation based on the tool health metric. 
     
     
       12. The method of  claim 11 , wherein generating the offset value further comprises generating a predetermined offset value responsive to the tool health metric being less than a predetermined threshold. 
     
     
       13. The method of  claim 11 , wherein generating the offset value further comprises generating the offset value having a magnitude proportionate to a difference between the tool health metric and a predetermined threshold. 
     
     
       14. The method of  claim 1 , wherein generating the control action further comprises generating an offset value for the measured output characteristic based on the tool health metric. 
     
     
       15. The method of  claim 14 , wherein generating the offset value further comprises generating a predetermined offset value responsive to the tool health metric being less than a predetermined threshold. 
     
     
       16. The method of  claim 14 , wherein generating the offset value further comprises generating the offset value having a magnitude proportionate to a difference between the tool health metric and a predetermined threshold. 
     
     
       17. The method of  claim 14 , wherein generating the tool health metric further comprises: 
       collecting tool state trace data during the processing of the second workpiece;  
       generating the tool health metric based on the tool state trace data; and  
       generating the offset value based on the tool health metric.  
     
     
       18. The method of  claim 17 , wherein generating the offset value further comprises: 
       comparing the collected tool state trace data to a library of reference tool state traces, each reference tool state trace having an associated offset value;  
       selecting a reference tool state trace closest to the collected tool state trace data; and  
       selecting the offset value associated with the selected reference tool state trace.  
     
     
       19. The method of  claim 5 , wherein generating the control action further comprises: 
       ignoring the measured output characteristic; and  
       setting the operating recipe parameter to a default value.  
     
     
       20. A method for controlling a process, comprising: 
       processing a first workpiece in a first process tool;  
       measuring an output characteristic of the first workpiece;  
       processing a second workpiece in the first process tool;  
       determining a tool health metric for the first process tool corresponding to the processing of the second workpiece;  
       determining a feedback control action for the first process tool based on the measured output characteristic and the tool health metric; and  
       decreasing an effect of the measured output characteristic on the feedback control action responsive to the tool health metric indicating a degraded condition of the first process tool.  
     
     
       21. The method of  claim 20 , wherein generating the feedback control action further comprises determining an operating recipe parameter of the first process tool for processing a subsequent workpiece. 
     
     
       22. The method of  claim 20 , wherein generating the feedback control action further comprises generating the feedback control action in accordance with a control equation based on at least the measured output characteristic, wherein decreasing the effect of the measured output characteristic further comprises reducing a sensitivity of the control equation based on the tool health metric. 
     
     
       23. The method of  claim 22 , wherein reducing the sensitivity further comprises reducing a gain constant of the control equation. 
     
     
       24. The method of  claim 22 , wherein reducing the sensitivity further comprises reducing the sensitivity responsive to the tool health metric being less than a predetermined threshold. 
     
     
       25. The method of  claim 22 , wherein reducing the sensitivity further comprises reducing the sensitivity in proportion to a difference between the tool health metric and a predetermined threshold. 
     
     
       26. The method of  claim 22 , wherein generating the feedback control action further comprises generating an offset value for the control equation based on the tool health metric. 
     
     
       27. The method of  claim 26 , wherein generating the offset value further comprises generating a predetermined offset value responsive to the tool health metric being less than a predetermined threshold. 
     
     
       28. The method of  claim 26 , wherein generating the offset value further comprises generating the offset value having a magnitude proportionate to a difference between the tool health metric and a predetermined threshold. 
     
     
       29. The method of  claim 20 , wherein generating the feedback control action further comprises generating an offset value for the measured output characteristic based on the tool health metric. 
     
     
       30. The method of  claim 29 , wherein generating the offset value further comprises generating a predetermined offset value responsive to the tool health metric being less than a predetermined threshold. 
     
     
       31. The method of  claim 29 , wherein generating the offset value further comprises generating the offset value having a magnitude proportionate to a difference between the tool health metric and a predetermined threshold. 
     
     
       32. The method of  claim 29 , wherein generating the tool health metric further comprises: 
       collecting tool state trace data during the processing of the second workpiece;  
       generating the tool health metric based on the tool state trace data; and  
       generating the offset value based on the tool health metric.  
     
     
       33. The method of  claim 32 , wherein generating the offset value further comprises: 
       comparing the collected tool state trace data to a library of reference tool state traces, each reference tool state trace having an associated offset value;  
       selecting a reference tool state trace closest to the collected tool state trace data; and  
       selecting the offset value associated with the selected reference tool state trace.  
     
     
       34. The method of  claim 21 , wherein generating the feedback control action further comprises: 
       ignoring the measured output characteristic; and  
       setting the operating recipe parameter to a default value.  
     
     
       35. A method for controlling a process, comprising: 
       processing a first workpiece in a first process tool;  
       measuring an output characteristic of the first workpiece;  
       processing a second workpiece in the first process tool;  
       determining a tool health metric for the first process tool corresponding to the processing of the second workpiece;  
       determining a feedforward control action for a second process tool to process at least the second workpiece based on the measured output characteristic and the tool health metric; and  
       decreasing an effect of the measured output characteristic on the feedforward control action responsive to the tool health metric indicating a degraded condition of the first process tool.  
     
     
       36. The method of  claim 35 , wherein generating the feedforward control action further comprises determining an operating recipe parameter of the second process tool for processing the second workpiece. 
     
     
       37. The method of  claim 35 , wherein generating the feedforward control action further comprises generating the feedforward control action in accordance with a control equation based on at least the measured output characteristic. 
     
     
       38. The method of  claim 37 , wherein decreasing the effect of the measured output characteristic further comprises reducing a sensitivity of the control equation based on the tool health metric. 
     
     
       39. The method of  claim 38 , wherein reducing the sensitivity further comprises reducing a gain constant of the control equation. 
     
     
       40. The method of  claim 38 , wherein reducing the sensitivity further comprises reducing the sensitivity responsive to the tool health metric being less than a predetermined threshold. 
     
     
       41. The method of  claim 38 , wherein reducing the sensitivity further comprises reducing the sensitivity in proportion to a difference between the tool health metric and a predetermined threshold. 
     
     
       42. The method of  claim 37 , wherein reducing the sensitivity further comprises generating an offset value for the control equation based on the tool health metric. 
     
     
       43. The method of  claim 42 , wherein generating the offset value further comprises generating a predetermined offset value responsive to the tool health metric being less than a predetermined threshold. 
     
     
       44. The method of  claim 42 , wherein generating the offset value further comprises generating the offset value having a magnitude proportionate to a difference between the tool health metric and a predetermined threshold. 
     
     
       45. The method of  claim 35 , wherein generating the feedforward control action further comprises generating an offset value for the measured output characteristic based on the tool health metric. 
     
     
       46. The method of  claim 45 , wherein generating the offset value further comprises generating a predetermined offset value responsive to the tool health metric being less than a predetermined threshold. 
     
     
       47. The method of  claim 45 , wherein generating the offset value further comprises generating the offset value having a magnitude proportionate to a difference between the tool health metric and a predetermined threshold. 
     
     
       48. The method of  claim 45 , wherein generating the tool health metric further comprises: 
       collecting tool state trace data during the processing of the second workpiece;  
       generating the tool health metric based on the tool state trace data; and  
       generating the offset value based on the tool health metric.  
     
     
       49. The method of  claim 48 , wherein generating the offset value further comprises: 
       comparing the collected tool state trace data to a library of reference tool state traces, each reference tool state trace having an associated offset value;  
       selecting a reference tool state trace closest to the collected tool state trace data; and  
       selecting the offset value associated with the selected reference tool state trace.  
     
     
       50. The method of  claim 36 , wherein generating the control action further comprises: 
       ignoring the measured output characteristic; and  
       setting the operating recipe parameter to a default value.